Carbon fluoride composition, paint, image forming material, complex material and method of manufacturing the same complex material

ABSTRACT

An image forming member for electrophotographic copying machines, facsimile machines and printers which has semi-conductivity, non-tackifying property and high dielectric property and therefore has high charging and image-transferring efficiency, is excellent in feeding property and separability of papers, is free from paper jamming and can give an excellent image stably; a paint used for the member; a carbon fluoride composition used for the paint; a composite material of fine particles of carbon fluoride; and a process for preparing the composite material are provided. The carbon fluoride composition comprises carbon fluorides and at least one selected from the group consisting of resins and rubbers and has semi-conductivity, non-tackifying property and a specific dielectric constant of not less than 10 at 25° C. at 1 kHz.

TECHNICAL FIELD

The present invention relates to a carbon fluoride composition, a paintcontaining the composition and an image forming member provided with asurface layer obtained by applying the paint. Also the present inventionrelates to a composite material comprising fine particles of carbonfluoride and a process for preparing the composite material.

BACKGROUND ART

A fluorine-containing resin and a fluorine-containing rubber haveexcellent properties such as heat resistance, oil resistance, solventresistance, chemical resistance and the like as compared with resins andrubbers for general uses, and are used widely as industrial materials inthe field where these properties are required. While making the best useof these excellent properties, further three properties such assemiconductivity, non-tackifying property and high dielectric propertyare demanded depending on applications.

For example, in the fields of image forming members forelectrophotographic copying machines, facsimile machines and printers, amaterial having well balanced properties such as semi-conductivity,non-tackifying property and high dielectric property is required forcharging members, transferring members and feeding members.

Namely a high dielectric property is required in order to conductcharging and image-transferring efficiently and feed papers securely.Also it is required that the material is semi-conductive in order toremove an induced charge immediately and prevent disturbance of an imagedue to occurrence of discharging at peeling off. Further in order toprevent contamination of each of the above-mentioned members by a tonerand paper dust, it is required not to lower the excellent non-tackifyingproperty which the fluorine-containing resin and fluorine-containingrubber possess inherently. Thus the above-mentioned members satisfyingall these three properties are demanded.

For example, JP-A-7-295391 discloses an image-transferring belt of athree-layer structure comprising an inner layer of a medium-resistantrubber material, a dielectric layer as an intermediate layer and anelectrically resistive layer as a surface layer containing dispersedcarbon particles in order to provide an image-transferring belt whichassures good feeding property and separability of papers and can give agood image stably. Also in case of a full-color copying machine and thelike, it is necessary to transfer a toner image formed on a surface ofan electrophotographic sensitive member onto an image-transferringmaterial by multi-color transfer of 3 or 4 colors, and therefore astep-up for changing transfer conditions is carried out with increase ina number of feedings and thus higher voltages are applied in order.Therefore the image-transferring member having a large dielectricconstant is desirable from the point that a large amount of electriccharges can be maintained at low voltage. JP-A-7-281535 discloses adielectric carrier article for image-transferring material which isobtained from a composition comprising a vinylidene fluoride resin and amethyl methacrylate resin in order to provide a dielectric article whichassures a small change of a volumetric resistivity against change inhumidity and temperature and has a high dielectric constant. AlsoJP-A-7-110582 discloses an electrostatically adsorbable and removablesheet which is used as an electrophotographic transfer sheet, paperadsorbing sheet of printers and the like and comprises a non-stretchedthin dielectric article obtained by melt-extruding a vinylidene fluorideresin and barium titanate powder in order to improve electrostaticallyadsorbing and removing characteristics and a tearing strength.

However there is a problem that any of the members described in thosepatent publications cannot satisfy the above-mentioned three properties.

Further JP-A-7-149448 discloses an electrically conductive andnon-tackifying roller in which an electrically resistive layercomprising a composition containing carbon fluoride particles with amolar ratio F/C of fluorine atom to carbon atom of more than 0.5 andless than 1.0 is provided on an electrically conductive supporting body.Though proper electric conductivity and non-tackifying property areobtained, it is desired to further improve a dielectric property. Alsoaccording to the process described in that publication, carbon fluorideparticles which are fluorinated only in their surface region or up tothe inside thereof uniformly and thus have a medium degree offluorination can be obtained. There is a problem, however, that even bycontrolling reaction conditions by any means, it is difficult to stablyobtain a mixture of highly fluorinated carbon fluoride particles andslightly fluorinated carbon fluoride particles.

Also in order to impart the above-mentioned semiconductivity to a resincomposition and rubber composition, an agent for imparting electricconductivity, for example, carbon black, carbon fiber, metal powder,ionic surfactant or the like has been used. In order to impart theabove-mentioned non-tackifying property, an agent for impartingnon-tackifying property, for example, a fluorine-containing oil, afluorine-containing resin such as tetrafluoroethylenehexafluoropropylenecopolymer, silicone oil or the like has been used. Further in order toimpart the above-mentioned high dielectric property, an agent forimparting a dielectric property, for example, lead zirconate titanatelanthanate, lead zirconate titanate, barium titanate or the like hasbeen used.

However in case where the three properties are needed at the same time,there are problems that not only a satisfactory performance cannot beobtained only by simply mixing the above-mentioned three agents but alsosince the above-mentioned agent for imparting conductivity and agent forimparting high dielectric property are substances having a high surfaceenergy, even if the agent for imparting non-tackifying property is used,lowering of the non-tackifying property cannot be avoided and even if afluorine-containing resin and fluorine-containing rubber are used as theabove-mentioned resin and rubber, only a composition havingnon-tackifying property lower than inherent non-tackifying property ofthe resin and rubber can be obtained.

An object of the present invention is to provide an image forming memberfor electrophotographic copying machines, facsimile machines andprinters. Because the member has semi-conductivity, non-tackifyingproperty and high dielectric property, the member has a high chargingefficiency and image-transferring efficiency, is excellent in feedingproperty and separability of papers, is free from jamming of papers andcan give a good image stably. The other objects are to provide a paintused for the member; a carbon fluoride composition used for the paint; acomposite material comprising fine particles of carbon fluoride; and aprocess for preparing the composite material.

DISCLOSURE OF THE INVENTION

The present invention relates to the carbon fluoride compositioncomprising carbon fluoride particles and at least one selected from thegroup consisting of resins and rubbers, said composition possessessemi-conductivity and non-tackifying property and has a specificdielectric constant of not less than 10 at 25° C. at 1 kHz.

Further the present invention relates to the paint comprising theabove-mentioned carbon fluoride composition and a liquid carrier.

Further the present invention relates to the image forming member forelectrophotographic copying machines facsimile machines and printerswhich comprises the electrically conductive supporting body having asurface layer formed by applying the paint.

Further the present invention relates to the composite materialcomprising fine particles of carbon fluoride, in which the compositematerial is covered with completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 and the inside of thecomposite material comprises a carbon fluoride fine particle orparticles having a F/C of not more than 0.1.

Further in the present invention, it is preferable that in preparing thecomposite material, the completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 are mixed simply with thecarbon fluoride fine particles having a F/C of not more than 0.1.

Further in the present invention, it is preferable that in preparing thecomposite material, the completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 are mixed with the carbonfluoride fine particles having a F/C of not more than 0.1, in water, inorganic solvent, in rubber or in molten resin.

Further the present invention relates to the composite materialcomprising fine particles of carbon fluoride in which the compositematerial is covered with completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 and the inside of thecomposite material comprises an electrically conductive fine particle orparticles having a particle size of at least 5 times the particle sizeof the completely fluorinated carbon fluoride fine particles.

Further in the present invention, it is preferable that in preparing thecomposite material, the completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 are simply mixed with theelectrically conductive fine particles having a particle size of atleast 5 times the particle size of the completely fluorinated carbonfluoride fine particles.

Further in the present invention, it is preferable that in preparing thecomposite material, the completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 are mixed with theelectrically conductive fine particles having a particle size of atleast 5 times the particle size of the completely fluorinated carbonfluoride fine particles, in water, in organic solvent, in rubber or inmolten resin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative view of an electrophotographic copying machinein which the semi-conductive roller of the present invention is used asa charging roller.

FIG. 2 is an outline cross-sectional view showing a layer configurationof the semi-conductive roller of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

A major feature of the carbon fluoride composition of the presentinvention is the use of a mixture of two kinds of carbon fluorideparticles, namely the completely fluorinated carbon fluoride particlesand the slightly fluorinated carbon fluoride particles having a molarratio of fluorine atom to carbon atom (hereinafter referred to as “F/C”)of less than 0.1. Thereby the image forming member forelectrophotographic copying machines, facsimile machines and printerswhich has a surface layer obtained by applying the paint containing theabove-mentioned composition (hereinafter referred to as “image formingmember” or “member”) is excellent in semi-conductivity, non-tackifyingproperty and particularly high dielectric property.

The above-mentioned high dielectric property means that a specificdielectric constant is not less than 10 at 25° C. at 1 kHz, and ispreferably from 10 to 10000, more preferably from 20 to 2000 though itvaries depending on application, coating thickness and electricresistance. When the specific dielectric constant is less than 10, incase where the composition is used for the member, for example, acharging member or image-transferring member, a charging efficiency andimage-transferring efficiency are lowered, a vivid image is difficult toobtain and a power source of higher voltage is necessary. Particularlyin case of full-color machines, in order to conduct multicolortransferring efficiently, higher specific dielectric constant isrequired. Also in feeding papers, a higher dielectric constant isrequired to efficiently conduct electrostatic adsorption and removal.When the specific dielectric constant is less than 10, a paper is notadsorbed securely, which results in jamming of the paper. The upperlimit of the specific dielectric constant is set to the value asmentioned above since an electrostatic capacity becomes higher thanrequired and a time constant becomes too large, and thus an electriccurrent necessary for charging and charge-removal becomes too large anda charging and charge-removal time becomes too long.

The semi-conductivity means a proper electric conductivity in which inthe above-mentioned member, charging and removing electric charge can beconducted efficiently. The semi-conductivity varies depending onapplication, coating thickness and dielectric constant in view of thetime constant, and a resistance can be set optionally within the rangeof from 10⁴ to 10¹² Ωcm. Further a difference in electric resistancebetween any points on surface of the member is within one order,preferably within a half order.

The non-tackifying property means that the above-mentioned members aredifficult to be contaminated with, for example, residual toners, paperdusts and the like, have non-tackiness to the extent of hardlyaccumulating the contaminant, and can be easily cleaned by usualcleaning apparatuses. The non-tackifying property is a property whichdoes not cause obstruction against charging and image-transferringfunctions. Though the non-tackifying property depends on the surfacecondition, at least one factor to be non-tackiness is an angle ofcontact to water which is not less than 90 degrees, more preferably notless than 100 degrees.

In order to prevent such contaminations, various cleaning mechanisms areusually provided. Use of the agents for imparting electric conductivityand high dielectric property leads to remarkable lowering ofnon-tackifying property and thereby increases importance of the cleaningmechanism, which results in obstructing downsizing of a printingapparatus and further shortens lives of the above-mentioned members.

Then explained below are carbon fluoride particles which can be used toobtain the well-balanced three properties mentioned above.

The carbon fluoride particles according to the present inventioncomprise poly(carbon monofluoride) as a main component, and preferableis one obtained by fluorinating a carbon material having an averageparticle size of not more than 1 μm, preferably not more than 0.1 μmwith a fluorine gas. In the carbon fluoride particles to be obtainedfrom carbon materials having an average particle size exceeding 1 μm,for example, petroleum cokes, graphite powder, carbon fiber and thelike, its amount has to be increased to impart semi-conductivity andnon-tackifying property to a resin or a rubber, and there is a tendencythat there occur disadvantages such as increased surface roughness,deterioration of mechanical strength, uneven resistivity, and the likeof the obtained composition.

The carbon material suitable for the carbon fluoride particles is acarbon black having the above-mentioned average particle size. As thecarbon black, there are used ones commercially available, for example,furnace black for rubbers (for example, Asahi #55 and the like made byAsahi Carbon Kabushiki Kaisha), channel black for color (for example,Leben 7000 made by Columbia Carbon Co., Ltd.), thermal black (SevacarboMT-C1 made by Columbia Carbon Co., Ltd.) and the like.

Among the carbon blacks, ones particularly generally called anelectrically conductive carbon black are preferable. The electricallyconductive carbon black is defined by using such factors that an averageparticle size is small (average particle size not more than 0.1 μm), asurface area is large (N₂ surface area not less than 50 m²/g), astructure is progressed (oil absorption amount not less than 100 cc/g),impurities content is small (ash content less than 0.1%) and forminginto graphite is advanced. Because the electrically conductive carbonblack can impart electric conductivity to materials in a relativelysmall mixing amount, it is used widely. Example thereof are onescommercially available, for instance, Ketjen Black EC and Ketjen BlackEC-600JD (available from Ketjen Black International Kabushiki Kaihsa),Black Purles 2000, Black Purles 3700 and Vulcan XC-72 (available fromCablack Kabushiki Kaisha), Denka Black, HS100 (available from DenkiKagaku Kogyo Kabushiki Kaisha), Conductex 950 (available from ColumbiaCarbon Co., Ltd.), #3030B (available from Mitsubishi Chemical Co., Ltd.)and the like.

In order to obtain the mixture of two kinds of carbon fluoride particleswhich can be used in the present invention, for example, there are

(1) a method of obtaining by one reaction operation,

(2) a method of obtaining by preparing two kinds of carbon fluorideparticles in separate reaction operations and then mixing them, and

(3) a method of obtaining by separating the mixture prepared in above(1) into two kinds of carbon fluoride particles and then re-mixing them.From the viewpoints of easy control of the reaction and easy operation,the method (2) is preferred.

In the above methods of (1) to (3), the fluorination is carried out by amethod of contacting fluorine gas to a carbon material, for example, acarbon black at a reaction temperature ranging from 200° to 600° C.,preferably from 300° to 500° C. When the reaction temperature is lowerthan 200° C., there occur problems that the fluorination reaction goesslowly, that a carbon fluoride having a covalent C—F bond is difficultto obtain, that the fluorination degree is difficult to increase since afluorine-graphite interrelation compound having an ionic or semi-ionicC—F bond is produced, that thermal stability is not sufficient and thatinherent non-tackifying property and lubricity of the carbon fluorideare not exhibited. On the contrary, when the reaction temperature ishigher than 600° C., thermal decomposition reaction is easy to occur, aproduction of a gaseous fluorocarbon compound occurs preferentially, andthus control of the reaction becomes difficult and a yield of theobtained carbon fluoride particles lowers. Also there are some caseswhere sudden and sharp thermal cracking reaction occurs resulting in anexplosion. Therefore it is necessary to pay attention to it.

The method (2) is carried out in such a manner that in the method (1),for example, at first the completely fluorinated carbon fluorideparticles are prepared by using sufficient amount of fluorine gas and asufficient reaction time, and separately the slightly fluorinated carbonfluoride particles are prepared by using a decreased amount of fluorinegas or a shortened reaction time, and then the slightly fluorinatedcarbon fluoride particles may be mixed with the completely fluorinatedcarbon fluoride particles.

The method (3) is carried out in the manner mentioned below. In themethod (1), for example, carbon fluoride particles fluorinated to acertain extent are prepared by controlling the reaction conditions. Atthat time, the completely fluorinated carbon fluoride particles can beobtained by scooping up with a spoon a reaction product tinged withwhite and existing in the upper part of a reaction vessel. Also slightlyfluorinated carbon fluoride particles can be obtained from the lowerpart in the reaction vessel. Each of carbon fluoride particles can alsobe obtained by dispersing the whole amount of the reaction product in aproper solvent and then centrifuging by using a difference in a specificweight. The two kinds of carbon fluoride particles obtained in such amanner may be mixed with each other.

In any of the methods (1) to (3), the fluorine gas used for the reactionmay be diluted with an inert gas such as nitrogen, argon, helium, carbontetrafluoride or the like or may contain a hydrogen fluoride. Thereaction can be conducted at normal pressure, and even under reducedpressure or under pressure, there is no problem with the reaction.

In the above methods, the reaction time, fluorine gas flow and the likemay be optionally adjusted depending on the reactivity of a startingmaterial, i.e. carbon material with fluorine and a desired F/C(calculated by using fluorine content mentioned hereinafter). Thepreferred reaction vessel is of box type made of nickel or monel alloyin which a carbon powder layer is allowed to stand and a fluorine gasdiluted properly is passed on the upper part of the powder layer. Also afluidized bed type and vibrating type in which the powder layer is movedcan be used.

The completely fluorinated carbon fluoride particles obtained by suchmethods do not increase its weight after completely fluorinated, has theF/C of not less than 1.0 and is tinged with white.

The slightly fluorinated carbon fluoride particles have the F/C of notmore than 0.1 and is tinged with black. Since a rising of temperatureoccurs due to a reaction heat depending on the reaction conditions,there is a case where a part of the produced slightly fluorinated carbonfluoride particles contain a highly fluorinated part, and such a partcan be removed by scooping, for example, with a spoon.

In the mixture of the two kinds of carbon fluoride particles, a weightratio of the completely fluorinated carbon fluoride particles to theslightly fluorinated carbon fluoride particles is from 1/99 to 99/1,preferably from 10/90 to 99/1.

Since the slightly fluorinated carbon fluoride particles are fluorinatedvery slightly, an interaction among particles thereof is weakened ascompared with the starting material, i.e. carbon black and even theslightly fluorinated carbon fluoride alone has good dispersibility andimproved properties in viscosity increasing and surface finishing of apaint. Thus these properties are the essential properties to distinguishthe slightly fluorinated carbon fluoride from a carbon black.

By mixing the completely fluorinated carbon fluoride particles with theslightly fluorinated carbon fluoride particles, high dielectricconstant, semi-conductivity and non-tackifying property which cannot beobtained from the individual carbon fluoride particles are exhibited.This is assumed to be that the mixture functions as a certain kind ofcomposite material comprising the fine particles. In this specification,an average degree of fluorination of this whole mixture is shown as adegree of fluorination of the carbon fluoride.

Also in the present invention, a fluorine content of carbon fluorideparticles is measured in the following manner. Carbon fluoride particlesare wrapped together with a combustion improver Na₂O₂ and polyethylenefilm and burned in a flask filled with oxygen. An amount of the producedhydrogen fluoride is measured with a fluoride ion meter (Ion Analyzer901 of Orion Corp.) through usual method. A fluorine content iscalculated from the obtained amount. Then the F/C is calculated based onthe obtained fluorine content.

As the resin or rubber used in the present invention, there arethermoplastic resins, thermosetting resins or rubbers.

The thermoplastic resins can be used advantageously as the materialsbeing high in processability since they can be plastically deformable byheating after once formed into a molded article. For example, there is afluorine-containing resin, polyamide, polyamideimide, polyacetal or thelike. Among them, the fluorine-containing resin is preferable from thepoints that it is excellent in heat resistance, chemical stability andnon-tackifying property and there is no change in these properties withthe lapse of time.

Examples of the fluorine-containing resins are polytetrafluoroethylene;copolymers of tetrafluoroetylene with at least one of othercopolymerizable ethylenically unsaturated monomer (for example, olefinssuch as ethylene and propylene, halogenated olefins such ashexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene andvinyl fluoride, and perfluoroalkyl vinyl ethers);polychloro-trifluoroethylene; polyvinylidene flouride; and the like.Particularly preferable flourine-containing resins arepolytetrafluoroethylene, copolymers of tetrafluoroethylene with at leastone of hexafluoropropylene, perfluoro(methyl vinyl ether),perfluoro(ethyl vinyl ether) and perfluoro(propyl vinyl ether)(containing generally in an amount of not more than 40% by mole withrespect to tetrafluoroethylene), and the like. When thefluorine-containing resin is used, there is exhibited an effect suchthat a composition having an excellent heat resistance, non-tackifyingproperty, water- and oil-repelling property, lubricity and chemicalresistance as compared with resins for general uses can be obtained.

As the polyamides, there can be used various materials commerciallyavailable as nylon resins. For example, there are 6 nylon, 66 nylon, 610nylon, 612 nylon, 11 nylon, 12 nylon, 46 nylon and the like. Alsoaramide wherein an aromatic component is introduced in a main chain, isencompassed therein. As the aramide, there are poly(paraphenyleneterephthalamide) and the like. These, though relatively inexpensive,exhibit effects such as an excellent heat resistance, high mechanicalstrength and excellent lubricity.

As the polyamideimide, there is, for example, Toron (available fromMitsubishi Kagaku Kabushiki Kaisha) obtained by the reaction oftrimellitic anhydride and aromatic diamine, and the like, which exhibitseffects such as a very high mechanical strength and heat resistance.

When the thermosetting resins are used, since they have athree-dimensional structure after being cured, they can allow propertiessuch as heat resistance, weatherability and chemical resistance and canbe used advantageously mainly as the paint composition. For example,there are silicone resins, phenol resins and the like.

As the silicone resins, there can be, for example, polymers generallycalled the silicone resins having a three-dimensional network structureand being obtained by hydrolyzing organosiloxane. As the commerciallyavailable ones, there are, for example, SR 2400 (available from TorayDow Corning Silicone Kabushiki Kaisha) and the like. Also there are onesbeing copolymerized with another organic resin generally called thesilicone modified resin. There are silicone alkyd resin, siliconepolyester resin, silicone epoxy resin and the like, depending on thekinds of organic resins to be copolymerized. As the commerciallyavailable resins, there are, for example, SR2100, SR2108, SR2115 (allavailable from Toray Dow Corning Silicone Kabushiki Kaisha) and the likewhich exhibit effect that low temperature curing is possible atrelatively low cost.

When the rubbers are used, because of elasticity of them, thecomposition can be endowed with property to be deformed by a smallstress and restored to the original state, and can be usedadvantageously as the materials for sealants, adhesives and rollers.Examples of the rubbers are ones for general uses, such as a siliconerubber or a fluorine-containing rubber, a styrene-butadiene rubber, apolyurethane rubber, a nitrile rubber, a chloroprene rubber, EPDM or thelike. Among them, the fluorine-containing rubber is preferable from thepoints that it is excellent in heat resistance, chemical stability andnon-tackifying property and there is no change in these properties withthe lapse of time.

As the silicone rubbers, there are various materials commerciallyavailable for sealants, coatings, formation of die and the like.

The silicone rubbers are generally classified into various grades,depending on their states and curing mechanisms, and are roughlyclassified into Mirable type silicone rubber and liquid form siliconerubber. The Mirable type silicone rubber is of a type heat-curing byadding a vulcanizing agent during the use, and is molded and processedin the same manner as in general organic rubbers. The Mirable typesilicone rubbers are used as materials for key pats of desk-topcalculators and the like and also rollers for an electrophotographiccopying machine. The liquid form silicone rubbers are in the form of aliquid having low density and requires no specific curing device. Theyare cured and formed into rubbers at room temperature or by heating, andare featured by excellent workability. There are two types of liquidform silicone rubbers, one component type and two component type, and asthe curing types, they are classified into a condensation type and anaddition type. The liquid form silicone rubbers are widely used asadhesives, sealants, coatings, potting agents and the like.

Both the Mirable type and liquid form silicone rubbers exhibit effectssuch as excellent electrical property as well as excellent heatresistance and cold resistance, good compression restoration property,chemical resistance, oil resistance and weatherability in a widetemperature range.

The fluorine-containing rubber is a highly fluorinated elasticcopolymer, and particularly preferable fluorine-containing rubbers areelastic copolymers of generally 40 to 85% by mole of vinylidene fluoridewith at least one of other copolymerizable fluorine-containingethylenically unsaturated monomers. The fluorine-containing rubber whichcontains iodide in the polymer chain also is, for instance, afluorine-containing rubber which mainly comprises an elastic copolymerof the same % by mole as mentioned above of vinylidene fluoride with atleast one of other copolymerizable fluorine-containing ethylenicallyunsaturated monomers, said copolymer being containing 0.001 to 10% byweight, preferably 0.01 to 5% by weight of iodide at its polymer end(JP-A-52-40543). Typical examples of the other ethylenically unsaturatedmonomers which are copolymerized with vinylidene fluoride to provide theelastic copolymers are hexafluoropropylene, pentafluoropropylene,trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, vinylfluoride, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether),perfluoro(propyl vinyl ether), and the like. Particularly preferablefluorine-containing rubbers are vinylidene fluoride/hexafluoropropyleneelastic copolymer and vinylidenefluoride/tetrafluoroetylene/hexafluoropropylene elastic copolymer. Theuse of the fluorine-containing rubbers gives effects such as excellentheat resistance and chemical resistance.

When the above-mentioned rubbers for general purposes are used, heatresistance, chemical resistance and the like are poor as compared withthe fluorine-containing rubbers, but a flexibility is easy to obtain andcost is low.

In the present invention, by combination use of the fluorine-containingresin and fluorine-containing rubber, effects of giving properflexibility and excellent non-tackifying property are exhibited.

In the present invention, the mixing ratio of the mixture of theabove-mentioned two kinds of carbon fluoride particles and a resinand/or rubber is 1/99 to 90/10 (weight ratio, hereinafter the same),preferably 5/95 to 50/50, particularly preferably 10/90 to 30/70. If themixing amount of the carbon fluoride particles becomes small, sufficienteffect of adding the carbon fluoride particles is not obtained, and ifit becomes too much, mechanical strength such as tensile strength tendsto lower.

Additives to be usually used may be added to the carbon fluoridecomposition of the present invention if necessary. As such additives,there are, for example, a vulcanizing agent, vulcanization accelerator,vulcanizing auxiliary, inorganic filler, releasing agent and the like.The mixing amount of the additives is not more than 20 parts by weight,preferably not more than 15 parts by weight based on 100 parts by weightof the resin and/or rubber. Also in order to enhance abrasionresistance, low molecular weight polytetrafluoroethylene can be added inan amount up to 20 parts by weight.

The carbon fluoride composition of the present invention is mixed andprepared by the usual method such as the following method.

(1) In case where a resin is used,

A resin, a mixture of two kinds of carbon fluoride particles and, ifnecessary, various additives are mixed in a mixer such as a V typeblender, tumbler and Henshel mixer and further mixed in a melt kneadersuch as a double screw extruder to give the carbon fluoride composition.

(2) In case where a rubber is used

A mixture of two kinds of carbon fluoride particles and, if necessary,various additives are added to a rubber for vulcanization in the form ofa solid, and mixed by the use of, for example, a banbury mixer or arubber roll to form into the homogeneous carbon fluoride composition.Also as another mixing method of these additives, there is a method topre-mix them with the rubber by a usual open roll and kneader and thenmix with other components.

The carbon fluoride composition of the present invention can be used forpaints. Further the paint can be used particularly suitably for anelectrically resistive layer of a semi-conductive roller ofelectrophotographic copying machines.

Also in case where fluorine-containing rubbers are used as the rubber, asemi-conductive, non-tackifying and highly dielectric carbon fluoridecomposition can be provided. The best mode in this case is explainedbelow.

The mixture of two kinds of carbon fluoride particles is mixedhomogeneously with a fluorine-containing rubber composition for thevulcanization by usual mixing method of a fluorine-containing rubbercomposition for the vulcanization, for example, with a banbury mixer,rubber roll or the like. Also as another mixing method of theseadditives, there is a method to pre-mix them with thefluorine-containing rubber by a usual open roll and kneader and then mixwith other components.

The thus homogeneously mixed carbon fluoride composition containing afluorine-containing rubber also can be used as a composition in the formof a liquid being dispersed or dissolved properly in water or organicsolvent.

This liquid composition can be used for the purpose of the presentinvention, being impregnated or coated onto paper, fiber cloth, film,sheet, plate, tube, pipe, container and other molded articles (Materialsof them to be used are synthetic resin, rubber (including afluorine-containing rubber), metal, ceramic and the like) to bevulcanized and deposited.

As the organic solvents, there can be used methyl ethyl ketone, acetone,cyclohexanone, amyl acetate, dioxane, tetrahydrofuran alone or incombination of not less than two kinds thereof.

As mentioned above, the carbon fluoride composition of the presentinvention which is obtained by using a fluorine-containing rubber can bevulcanized under usual conditions in accordance with the known methodfor vulcanizing a fluorine-containing rubber, and the intendedvulcanized rubber having semi-conductivity, non-tackifying property andhigh dielectric property is obtained without impairing variousproperties inherent to rubbers.

Also in the carbon fluoride composition of the present invention, it ispreferable that a difference in a volumetric resistance between anypoints on surface of the member is within one order in the range of 10⁴to 10¹² Ωcm. If the volumetric resistance deviates from the above range,a vivid image cannot be obtained even in case of high dielectricconstant. Namely in case of less than 10⁴ Ωcm, an electric chargegenerated on the surface of the member immediately scatters. Thus notonly effective charging and image-transferring cannot be carried out butalso an increase in load of a power source is resulted. In case of morethan 10¹² Ωcm, an electric charge generated on the surface of the memberremains there in an amount more than required and a disturbance of animage due to discharging at peeling off occurs.

Suitable dielectric constant and volumetric resistance vary depending onan equipment and part to be used, or paper feeding speed and the like.Also the suitable volumetric resistance differs depending on the setdielectric constant.

The present invention further relates to a paint containing theabove-mentioned carbon fluoride composition and a liquid carrier.

The liquid carrier is mixed since it is suitable for various paintingworks such as spray coating, brush coating and dip coating. Examplesthereof are, for instance, lower ketones such as acetone, methyl ethylketone and cyclohexanone; lower esters such as ethyl acetate, propylacetate, and butyl acetate; cyclic ethers such as tetrahydrofuran and1,4-dioxane; water; a mixture of water with alcohols such as methanol,ethanol and isopropyl alcohol, glycols such as ethylene glycol and watersoluble organic liquid such as methyl cellosolve; and not less than twokinds thereof. Particularly preferable liquid carrier is one comprisingwater as a main component from the viewpoint of painting workability,storage stability, protection of global environment and the like.

The content of the carbon fluoride composition in the paint of thepresent invention may be properly selected in consideration of paintingworkability, film forming property and the like, and is generally 10 to70% by weight, preferably 30 to 60% by weight.

Further additives which are usually mixed in various paints, may beadded depending on uses. As these additives, there are, for example,pigments, adhesion enhancing agents (organic resin powder and the like),lubricity imparting agents (fluorine-containing oil and the like),abrasion resistance enhancing agents (inorganic ceramic powder and thelike), thickener, film forming agents, surfactants and the like. Themixing amounts of them may be suitably selected depending on uses,coating methods and the like. Attention is to be paid not to impair theintended semi-electric conductivity, non-tackifying property and highdielectric property of the present invention.

Then with respect to one example of the paint of the present invention,explanation is made on a fluorine-containing rubber paint in case wherea fluorine-containing rubber is used as the component of the carbonfluoride composition.

The liquid carrier to be used is selected from the above-mentionedorganic solvents such as lower ketone, lower ester and cyclic ether,water and a mixture of water and water soluble organic liquid. As thewater soluble organic liquid, there are alcohols. Among these liquidcarriers, water and one comprising water as a main component are mostpreferable from a point that no painting workability is impaired.

Inorganic fibrous substances as the other substances being contained inthe fluorine-containing rubber paints are used to enhance compressionrestoration property of a fluorine-containing rubber coating. As thetypical substances, there are glass fibers, carbon fibers, asbestosfibers, potassium titanate fibers, and the like. It is desirable that anaverage length of this inorganic fibrous substance is at least 1 μm,preferably 1 to 100 μm.

Amine compounds to be added, if desired, in the fluorine-containingrubber paint are intended to function mainly as the vulcanizing agent ofthe fluorine-containing rubber and improve mechanical property togetherwith the above-mentioned coupling agent. Typical examples of suchcompounds are mono-amines such as ethyl amine, propyl amine, butylamine, benzyl amine, allylamine, n-amyl amine and ethanolamine, diaminessuch as ethylenediamine, trimethylenediamine, tetramethylenediamine,hexamethylenediamine and3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5,5]undecane andpolyamines such as diethylenetriamine, triethylenetetramine,tetraethylenepentamine and pentaethylenehexamine. Particularly aminecompounds having two or more of terminal amino groups are preferable.

The fluorine-containing rubber paints are made homogeneous by usuallymixing an electrically conductive substance, pigment, acid acceptor,filler and the like (in addition, surfactant may be used if necessary)with a mixture of a fluorine-containing rubber, fluorine-containingresin and liquid carrier, adding a coupling agent and, if necessary,amine compound (if necessary, the above-mentioned additives such aspigment, acid acceptor and filler may be added) to the obtaineddispersion solution, and then mixing sufficiently by usual method.

The weight ratio of the fluorine-containing rubber to thefluorine-containing resin is desirably from 95/5 to 35/65. When theratio of the fluorine-containing resin is lower than the above-mentionedlower limit, the intended improvement of non-tackifying property andlubricity is not sufficient. On the contrary, when higher than thementioned upper limit, the intended coating thickness cannot be obtainedand cracks and pin holes are easy to occur on the coating.

The adding amount of the mixture of the above-mentioned two kinds ofcarbon fluoride particles can be changed depending on uses of paints andkinds of electrically conductive substances. The mixture of carbonfluorides may be added so that the volume specific resistance of thefluorine-containing rubber coating is not more than 10⁸ Ωcm for thepurpose to prevent charging, and not more than 10² Ωcm in case of usingas a plate heater.

The coupling agent is usually added in an amount of 1 to 50 parts byweight, preferably 1 to 20 parts by weight based on 100 parts by weightof a fluorine-containing rubber. In case where an amine compound isdesired to be added, the amine compound and coupling agent are mixed sothat a total amount of them becomes the value mentioned above. In thiscase, the mole ratio of the coupling agent to the amine compound isselected from the range of 1/99 to 99/1.

As the above-mentioned acid acceptor, there is used one usually used forthe vulcanization of fluorine-containing rubbers in the same manner. Forexample, one or two or more kinds of bivalent metal oxides or hydroxidesare used. Concretely there are oxides or hydroxides of magnesium,calcium, zinc, lead and the like. Also as the above-mentioned filler,there are used silica, clay, diatom earth, talc, carbon and the like.

The fluorine-containing paints are coated or impregnated onto thesubstrate by usual coating methods (brush coating, dipping, spraying andthe like), and the intended fluorine-containing rubber coating can beobtained by curing under a temperature condition of from roomtemperature to 400° C., preferably from 100° to 400° C. for a suitableperiod of time.

Coating thickness of the fluorine-containing rubber paints is preferablynot less than 5 μm. If the coating thickness is less than 5 μm, there isa fear that unevenness occurs on the whole surface of the substrate andthere occurs uncoated part. The thus obtained fluorine-containing rubbercoating has semi-electric conductivity, non-tackifying property and highdielectric property in addition to properties inherent tofluorine-containing rubbers such as heat resistance, weatherability,abrasion resistance, oil resistance, solvent resistance and chemicalresistance, and is excellent in adhesivity to the substrate andmechanical property of the coating itself and is further endowed withlubricity on the coating surface.

The coupling agent is a compound acting on an interface between theorganic material and the inorganic material and forming a more rigidbridge between both the materials rather than chemical or physicalbonding. The coupling agent is usually a compound of silicon, titanium,zirconium, hafnium, trium, tin, aluminum or magnesium, and a compoundhaving a group being capable of bonding the organic and inorganicmaterials. Among these coupling agents, preferable is silane couplingagent, and ortho-acid esters of transition elements of the group IV ofthe periodic table (for example, titanium, zirconium and the like) andtheir derivatives. Particularly an aminosilane compound is mostpreferable.

As the silane coupling agents, there can be, for example, silanecompounds shown by the formula:

R¹.Si.R² _(3-a).R³ _(a)

(wherein, R¹ is an alkyl group or a vinyl group having 1 to 10 carbonatoms and at least one kind functional atom or group selected fromchlorine atom, amino, aminoalkyl, ureide, glycidoxy, epoxy cyclohexyl,acryloyloxy, methacryloyloxy, mercapto and vinyl, R² and R³ arerespectively an atom or group selected from chlorine atom, hydroxyl,alkoxyl having 1 to 10 carbon atoms, alkoxy-substituted alkoxyl having 2to 15 carbon atoms, hydroxyalkyloxyl having 2 to 4 carbon atoms andacyloxyl having 2 to 15 carbon atoms, a is 0, 1 or 2).

R¹ is an alkyl group having a functional substituent, and suitableexamples thereof are β-aminoethyl, γ-aminopropyl,N-(β-aminoethyl)-γ-aminopropyl, γ-ureidopropyl, γ-glycidooxypropyl,β-(3,4-epoxycyclohexyl)ethyl, γ-acryloyloxypropyl,γ-methacryloyloxypropyl, γ-mercaptopropyl, β-chloroethyl,γ-chloropropyl, γ-vinylpropyl and the like. Also R¹ may be a vinylgroup.

Examples of the above-mentioned silane compounds to be suitably usedare, for instance, γ-aminopropyltriethoxysilane,N-β-aminoethyl-γ-aminopropyltrimethoxysilane,γ-ureidopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane,γ-(3,4-epoxycyclohexyl)ethyltrimethylsilane,γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltrimethdxysilane,γ-chloropropyltrimethoxysilane, vinyltris(β-methoxyethoxy)silane,vinyltriethoxysilane, vinyltrichlorosilane, vinyltriacetoxysilane,N-(trimethoxysilylpropyl) ethylenediamine,N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane andβ-aminoethyl-β-aminoethyl-γ-aminopropyltrimethoxysilane. Among thesesilane coupling agents, aminosilane compounds, for example,γ-aminopropyltriethoxysilane,N-β-aminoethyl-γ-aminopropyltrimethoxysilane,N-(trimethoxysilylpropyl)ethylenediamine,N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane,γ-ureidopropyltriethoxysilane,β-aminoethyl-β-aminoethyl-γ-aminopropyltrimethoxysilane and the like areparticularly preferable, because they function as the vulcanizing agentsfor the fluorine-containing rubbers, contribute to enhance adhesivity tothe substrate, and further are used safely against the liquid carrier.

As the compounds of titanium, zirconium, hafnium and trium, there can bementioned, for example, ortho acid esters shown by the formula:

T(OR)₄

(wherein, T is titanium, zirconium, hafnium or trium, R shows alkyl,cycloalkyl or allyl) and derivatives to be obtained by reacting themwith one or more compounds having at least one functional group. As theabove-mentioned compounds having at least one functional group, therecan be used polyhydric alcohols such as glycerine, ethylene glycol,1,3-butanediol, 2,3-butanediol, hexylene glycol and octylene glycol,oxyaldehydes such as salicylaldehyde and glycose, oxyketones such asdiacetone alcohol and fructose, oxycarbonic acids such as glycolic acid,lactic acid, dioxy maleic acid and citric acid, diketones such asdiacetylacetone, ketones such as acetoacetate, esters of ketonic acidssuch as acetoacetic ethyl, oxyamines such as triethanolamine anddiethanolamine, and oxyphenol compounds such as cathecol and pyrogallol.

Concrete examples of the compounds in case where T is titanium, aretetraalkyltitanate (for example, tetraethyl titanate, tetraisopropyltitanate and tetrabutyl titanate), tetraethyleneglycol titanate,triethanolamine titanate, titanium acetylacetonate, isopropyltrioctanoyltitanate, isopropyl trimethacryl titanate, isopropyltriacryl titanate,isopropyltri(butyl, methylpyrophosphate) titanate,tetraisopropyldi(dilaurylphosphite) titanate, dimethacryloxy acetatetitanate, diacryloxy acetate titanate, di(dioctylphosphate) ethylenetitanate and the like.

As the zirconium compounds, there can be used the same compounds as theabove-mentioned titanium compounds. Examples thereof are tetraalkylzirconates such as tetraethyl zirconate and tetrabutyl zirconate,n-propyl zirconate, isopropyl zirconate, n-butyl zirconate, isobutylzirconate, zirconium acetylacetonate and the like.

As the compounds of hafnium and trium, there can be used the samecompounds as the titanium and zirconium compounds.

As the tin compounds, there can be used organic or inorganic compounds,for example, SnCl₄ and the like. As the aluminum compounds, there can bementioned aluminum isopropylate, monosec-butoxyaluminum diisopropylate,aluminumsec-butylate, ethylacetoacetate aluminum diisopropylate,aluminumtris (ethylacetoacetate) and the like.

As the magnesium compounds, there can be mentioned magnesium alcoholatessuch as magnesium methylate and magnesium ethylate.

The semi-electric conductivity of the above-mentionedfluorine-containing rubber paint has a feature that the resistivity canbe easily controlled to be a desired value by selecting the kinds of thetwo kinds of carbon fluoride particles to be mixed, fluorine content andmixing amount.

Also this fluorine-containing rubber paint has a feature that by itsexcellent dispersibility as the paint and a little increase in paintviscosity, coating is easy and as a result, a coating having uniformproperty can be obtained easily.

The fluorine-containing rubber paint is as referred to hereinabove, andthe paint of the present invention can also be produced in the samemanner when other resins or rubbers than the fluorine-containing rubbersare used.

Mentioned below are descriptions relating to only characteristic mattersof each resin and rubber. Other technical matters and conditions aresubstantially the same as those of the fluorine-containing rubber paint,and it is possible to make a design change obvious to a person skilledin the art.

As one example of the paint of the present invention, explained below isthe case where a fluorine-containing resin is used as the component ofthe carbon fluoride composition.

Examples of the fluorine-containing resins are polytetrafluoroethylene;copolymers of tetrafluoroetylene with at least one of othercopolymerizable ethylenically unsaturated monomer (for example, olefinssuch as ethylene and propylene, halogenated olefins such ashexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene andvinyl fluoride, and perfluoroalkyl vinyl ethers);polychlorotrifluoroethylene; polyvinylidene flouride; and the like.Particularly preferable flourine-containing resins arepolytetrafluoroethylene, copolymers of tetrafluoroethylene with at leastone of hexafluoropropylene, perfluoro(methyl vinyl ether),perfluoro(ethyl vinyl ether) and perfluoro(propyl vinyl ether)(containing generally in an amount of not more than 40% by mole withrespect to tetrafluoroethylene), and the like.

The liquid carrier is mixed since it is suitable for various paintingworks such as spray coating, brush coating and dip coating. Examplesthereof are, for instance, lower ketones such as acetone, methyl ethylketone and cyclohexanone; lower esters such as ethyl acetate, propylacetate, and butyl acetate; cyclic ethers such as tetrahydrofuran and1,4-dioxane; water; a mixture of water with alcohols such as methanol,ethanol and isopropyl alcohol, glycols such as ethylene glycol and watersoluble organic liquid such as methyl cellosolve; and not less than twokinds thereof. Particularly preferable liquid carrier is one comprisingwater as a main component from the viewpoint of painting workability,storage stability, protection of global environment and the like.

In addition, surfactants, pigments, fillers and various paintingadditives can be added if necessary.

Further additives which are usually mixed in various paints, may beadded depending on uses. As these additives, there are, for example,pigments, adhesion enhancing agents (organic resin powder and the like),lubricity imparting agents (fluorine-containing oil and the like),abrasion resistance enhancing agents (inorganic ceramic powder and thelike), thickener, film forming agents, surfactants and the like. Themixing amounts of them may be suitably selected depending on uses,coating methods and the like. Attention is to be paid not to impair theintended semi-conductivity, non-tackifying property and dielectricproperty of the present invention.

The adding amount of the mixture of the two kinds of carbon fluorideparticles can be changed depending on uses of paints, a kind of thecarbon fluoride particles and the degree of the fluorination. The carbonfluoride may be added so that the volume specific resistance is not morethan 10⁸ μm for the purpose to prevent electric charging.

In case where polyamides are used as the component of the carbonfluoride composition for the paint of the present invention, paints canbe prepared in the same manner as in the above-mentionedfluorine-containing resin. Also it is possible to previously combine themixture of the two kinds of carbon fluoride particles with polyamidefine particles by a dry method to give composite fine particle materialsand then disperse them in the liquid carrier by a proper method. As thepolyamide fine particles to be used in this case, there can be mentionedfine particles of a spherical form, for example, SP-500 (available fromToray Kabushiki Kaisha). For the combining method, for example,Hybridizer (available from Kabushiki Kaisha Nara Kikai Seisakusho),Mechanomill (available from Okada Seiko Kabushiki Kaisha) and the likecan be used. The feature of this method is such that since compositefine particle materials are previously prepared, they are mixedhomogeneously, and a uniform coating is easily obtained irrespective ofpaints being in a dispersed state.

Also in case where polyamideimides are used as the component of thecarbon fluoride composition for the paint of the present invention, inthe same manner as in case of the above-mentioned fluorine-containingresins and polyamides, the polyamideimides not only are used alone, butalso are mixed with fluorine-containing resins for use as a primer paintfor a fluorine-containing resin paint or are mixed with thermoplasticresins such as polyamides to improve mechanical property.

In case where silicone resins or silicone rubbers are used as thecomponent of the carbon fluoride composition for the paint of thepresent invention, an organic solvent mainly such as toluene or siliconeoil having a low boiling point is used as the liquid carrier. The carbonfluoride compositions added together with a catalyst (for example, zincoctylate) and various additives to a commercially available compositionfor curing (for example, SR-2400, available from Toray Dow CorningInternational Kabushiki Kaisha), and fully dispersed in triple rolls andthe like. The solvent such as toluene is added to give a paint having aviscosity conforming to a coating method. After the painting, the paintis cured at a specified temperature (for example, 235° C., for 1 hour).

With regard to rubbers for general uses, the mixing can be carried outin compliance with properties of each rubber in the same manner as inthe above-mentioned fluorine-containing rubber and silicone rubber.

Further the present invention relates to an image forming member forelectrophotographic copying machines, facsimile machines and printerswhich is obtained by applying the above-mentioned paint on anelectrically conductive supporting body to form a surface layer thereon.

Examples of the image forming member for the electrophotographic copyingmachines, are for instance, a charging roller, image-transferringroller, fixing roller, resist roller, developing roller, paper feedroller, electrically conductive belt, dielectric belt,image-transferring belt, photosensitive belt, fixing belt, toner feedbelt, paper feed belt, paper supplying belt, image-transfer sheet, paperadsorption sheet, sheet-like member, charged magnetic brush, chargedfiber brush, magnetic particles for a charging member and the like.

Examples of the image forming member for the facsimile machines, are forinstance, a charging roller, image-transferring roller, fixing roller,resist roller, developing roller, paper feed roller, electricallyconductive belt, dielectric belt, image-transferring belt,photosensitive belt, fixing belt, toner feed belt, paper feed belt,paper supplying belt, image-transfer sheet, paper adsorption sheet,sheet-like member, charged magnetic brush, charged fiber brush, magneticparticles for a charging member and the like.

Examples of the image forming member for the printers, are for instance,a charging roller, image-transferring roller, fixing roller, resistroller, developing roller, paper feed roller, electrically conductivebelt, dielectric belt, image-transferring belt, photosensitive belt,fixing belt, toner feed belt, paper feed belt, paper supplying belt,image-transfer sheet, paper adsorption sheet, sheet-like member, chargedmagnetic brush, charged fiber brush, magnetic particles for a chargingmember and the like.

An electrophotographic copying machine using a contact charge method hasa structure as stated, for instance, in JP-A-4-311972. The structurethereof is, for example, one as shown in FIG. 1. A photosensitive drum 1usually comprises an organic photoreceptor, and there may be usedselenium, CdS, amorphous silicon and the like. A charging roller 2 isdisposed being brought into contact with the above-mentionedphotosensitive drum 1. A developing device 3, an image-transferringroller 5 and a toner cleaner 7 are arranged in the clockwise direction,centering around the charging roller 2. Further a fixing roller 6 forfixing of an image-transferred paper 4 fed out from the transferringroller 5 is disposed in the vicinity of the photosensitive drum 1between the transferring roller 5 and the toner cleaner 7.

The image forming process of the electrophotographic method using thesemi-conductive roller is briefly explained hereinbelow.

The charging roller 2 comprising the semi-conductive roller having anelasticity is rotated on the outer circumferential surface of thephotoconductive drum 1 (for instance, linear speed 60 mm/sec) rotatingin the direction of an arrow, by the photosensitive drum 1, being partlyelastically deformed. The outer surface of the photosensitive drum 1 iselectrically charged by bringing it into contact with this chargingroller 2. On the surface of the thus charged photosensitive drum 1 isformed an electrostatic latent image corresponding to an original imageby means of an exposing mechanism portion 8, and this latent image ismade into a visible image by a developing device 3. Then an electriccharge reverse to the visible image of toner particles which is formedon the photosensitive drum 1 is applied to a transfer paper 4 throughthe tansferring roller 5 to transfer the visible image of the tonerparticles onto the transfer paper 4. The visible image of the tonerparticles electrostatically sticking to the transfer paper 4 is fusedand deposited on the transfer paper 4 by the heated fixing roller 6 togive a fixed image.

In this case, 85 to 95% of the toner sticking onto the surface of theabove-mentioned photosensitive drum 1 by means of the transferringroller 5 is transferred on the drum but the remaining toner after thistransfer is nearly completely removed by means of a toner cleaner 7,then is wholly subjected to an emission of light by an eraser 9, andinitiated to make preparation for the subsequent charging.

As mentioned above, for the electrophotographic copying machine and thelike, there are used many semiconductive rollers such as the chargingroller, developing roller, transferring roller and fixing roller. Asshown in FIG. 2, such a semi-conductive roller to be used is such that ametallic core roll 10 and an electrically conductive elastic layer 11 onthe outer circumference thereof are formed and an electrically resistivelayer 12 is formed over this electrically conductive elastic layer 11.

In the above-mentioned roller, the electrically conductive elastic layeris first formed on the electrically conductive supporting body.Materials of this electrically conductive elastic layer is notparticularly limited, and this layer comprises a composition prepared bymixing electrically conductive powder and fiber (carbon black, metalpowder, carbon fiber and the like) in a synthetic rubber such assilicone rubber, ethylene propylene rubber, epichlorohydrine rubber,nitrile rubber and urethane rubber. This layer has a volume specificresistance of not more than 10⁵ Ωcm, preferably not more than 10³ Ωcmand a rubber hardness (JIS A) in the range of 20 to 50 degrees,preferably 25 to 40 degrees. It is not preferable to use a plasticizerand surfactant for the purposes of adjusting a resistance and a rubberhardness when mixing the electrically conductive powder and the like.This is because these chemicals bleed out with the lapse of time,resulting in the contamination of the surface of the photoreceptor andthe occurrence of toner filming on the surface of the roller.

The materials of the electrically conductive supporting body are notparticularly limited, and aluminum or an alloy comprising aluminum as amain component or stainless steel can be used.

Then the method for producing the above-mentioned roller is explainedbelow. (i) At first, as the material for the electrically conductiveelastic layer, for instance, a peroxide vulcanizing agent is added to arubber compound prepared by dispersing a carbon black in aheat-vulcanizing silicone rubber, and then kneaded sufficiently withtwin rollers to obtain a carbon black-dispersed rubber compound having ahomogeneous composition. (ii) This rubber compound is wound on an outercircumference of a metal core roll, and put in a die for molding theroller which has been preheated (for instance, 170° C.). Then aspecified pressure (for instance, 120 kg/cm²) is applied to carry out afirst vulcanization (for instance, for 10 minutes). (iii) Then thepressure applied to the die is relieved, and the roller is taken out tocarry out a second vulcanization (for instance, 200° C., for 4 hours).(iv) After that, the surface of the roller is polished, and the requiredoutside dimensions are obtained and at the same time, the surfaceroughness is made to be not more than 10 μm (Rz). (v) Afterwards theelectrically conductive non-tackifying composition as the material forthe electrically resistive layer is coated on the outer circumference ofthe electrically conductive elastic layer obtained in (iv) with airspray (or dipping method) (coating thickness 30 to 200 μm), andsintering is conducted under the specified conditions (for instance,300° C., for 20 minutes). As the sintering method, in order to minimizeheat deterioration of the electrically conductive elastic layer, it isdesirable to properly use an infrared image oven.

In case where the above-mentioned roller is used as, or example, thesemi-conductive roller of the electrophotographic copying machine of thepresent invention, it is preferable to use the above-mentioned paintcontaining the carbon fluoride composition as a material for theelectrically resistive layer of above (v) and use a fluorine-containingpolymer such as a fluorine-containing resin or fluorine-containingrubber as the resin or rubber in the composition because excellentnon-tackifying property and heat resistance against the toners,durability and the like can be obtained and the roller has excellentsemi-conductivity, particularly high dielectric property.

Also, in case where the electrically resistive layer is formed by addingand dispersing the mixture of two kinds of carbon fluoride particles inthe fluorine-containing polymer, electric conductivity can be controlledby the carbon fluoride, and also an electric breakdown is hard to occurbecause of an enhanced dispersibility and the deterioration ofnon-tackifying property against the toners is solved. Further it is asurprise that abrasion resistance is enhanced as compared with afluorine-containing polymer alone, and sufficient property as thesemi-conductive roller can be exhibited.

Further when the thermoplastic resins such as polyamide andpolyamideimide, thermosetting resins such as a silicone resin, siliconerubbers and rubbers for general uses are used besides thefluorine-containing polymers, they are useful as the electricallyresistive layer of the semi-conductive roller because non-tackifyingproperty and lubricity of the carbon fluoride function additionally.However among these resins, there are ones having heat resistance andstability of chemical and electrical properties being inferior ascompared with the fluorine-containing polymer, and therefore for thesemiconductive rollers produced using these resins, considerations arerequired for the operating conditions and the position where the rollersare used.

Further the present invention relates to the composite materialcomprising fine particles of carbon fluoride, in which the compositematerial is covered with completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 and the inside of thecomposite material comprises a carbon fluoride fine particle orparticles having a F/C of not more than 0.1.

Further in the present invention, it is preferable that in preparing thecomposite material, the completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 are mixed simply with thecarbon fluoride fine particles having a F/C of not more than 0.1.

Further in the present invention, it is preferable that in preparing thecomposite material, the completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 are mixed with the carbonfluoride fine particles having a F/C of not more than 0.1, in water, inorganic solvent, in rubber or in molten resin.

Further the present invention relates to the composite materialcomprising fine particles of carbon fluoride in which the compositematerial is covered with completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1, and the inside of thecomposite material comprises an electrically conductive fine particle orparticles having a particle size of at least 5 times the particle sizeof the completely fluorinated carbon fluoride fine particles.

Further in the present invention, it is preferable that in preparing thecomposite material, the completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 are simply mixed with theelectrically conductive fine particles having a particle size of atleast 5 times the particle size of the completely fluorinated carbonfluoride fine particles.

Further in the present invention, it is preferable that in preparing thecomposite material, the completely fluorinated carbon fluoride fineparticles having a F/C of not less than 1 are mixed with theelectrically conductive fine particles having a particle size of atleast 5 times the particle size of the completely fluorinated carbonfluoride fine particles, in water, in organic solvent, in rubber or inmolten resin.

Examples of the preferred carbon fluoride composition of the presentinvention are, for instance, those mentioned below.

(A) At least one selected from the group consisting of resins andrubbers

(B) Carbon fluoride particles

This composition is advantageous in that it has excellentsemi-conductivity and non-tackifying property and a specific dielectricconstant is not less than 10 at 25° C. at 1 kHz.

More preferably,

(A1) Fluorine-containing resin and/or fluorine-containing rubber

(B1) Mixture of completely fluorinated carbon fluoride particles andcarbon fluoride particles having the F/C of not more than 0.1

This composition is excellent in heat resistance, chemical stability,non-tackifying property, semi-conductivity and high dielectric property.

The present invention is then explained by means of examples, but is notlimited to them.

EXAMPLES 1 TO 8 Dielectric Property of Coating Film

A hundred grams of Ketchen Black EC (available from Ketchen BlackInternational) was spread uniformly in a box type reactor made of moneland then heated up to 400° C. with flowing nitrogen gas. Then, fluorinegas and nitrogen gas were flowed at 200 ml/min and 1800 ml/min,respectively for one hour to carry out a fluorination reaction.Immediately after the reaction, the inside of the reactor was replacedwith nitrogen gas and was cooled down to room temperature with flowingnitrogen gas. Then a reaction product was taken out. The reactionproduct was slightly fluorinated carbon fluoride particles having theF/C of 0.08.

Also completely fluorinated carbon fluoride particles having the F/C of1.15 were prepared under the same conditions except that the reactiontime was 23 hours.

The completely fluorinated carbon fluoride particles and slightlyfluorinated carbon fluoride particles were mixed in calculated amountsand tumbled in a polyethylene bag sufficiently to give a carbon fluoridemixture having the average F/C of 0.5 (Examples 1 to 4). Also bychanging a mixing ratio, the carbon fluoride particles having the F/C of0.1 (Example 5), 0.3 (Example 6), 0.7 (Example 7) and 0.9 (Example 8),respectively were obtained.

Then with 30 g of a green rubber of fluorine-containing rubber (DaielG501NK available from Daikin Industries, Ltd.), the carbon fluoridemixture having the F/C of 0.5 in an amount of 1.8 g (6% based on thegreen rubber) (Examples 1 and 5 to 8), 3.6 g (12% based on the greenrubber) (Example 2), 5.4 g (18% based on the green rubber) (Example 3)or 7.2 g (24% based on the green rubber) (Example 4), and 1.5 g ofhydrotalcite (DHT-4A available from Kyowa Chemical Industry Co., Ltd.)were mixed, and then a butyl acetate was added to give 300 g of amixture. Then the mixture was pulverized for 48 hours in a magnetic ballmill (ø150) to give a paint.

This paint was applied to a surface of an aluminum plate by anapplicator, and after drying at 65° C. for 30 to 40 minutes, was bakedat 200° C. for 30 minutes to give coating of Examples 1 to 4. Withrespect to the coatings, the following measurements were made.

(Method of measuring electric conductivity)

Analyzer: R8340A (available from Advantest) and 196 System DMM(available from Keithley Corp.)

Electrode: R12702A (available from Advantest Kabushiki Kaisha)

Pressure of electrode: 3 to 4 kgf

Applied voltage: 10V

Charging time: 1 minute

Measurement was made according to JIS K6911.

(Method of measuring dielectric constant)

Analyzer: HP4194A, HP4274A (available from Hewlett Packard Japan, Co.,Ltd.)

Electrode: HP16451B (available from Hewlett Packard Japan, Co., Ltd.)

Electrode size: ø5 mm (Electrode B)

Frequency: 1 kHz

Measurement was made according to JIS C2317.

The results are shown in Tables 1 to 3.

TABLE 1 Added amount of carbon Coating Specific dielectric fluoridethickness Electrostatic capacity Dielectric loss constant mixture (μm) 1kHz 1 MHz 10 MHz 1 kHz 1 MHz 10 MHz 1 kHz 1 MHz 10 MHz Ex. 1  6% 15 2921.76 19.7 0.04 0.114 0.11 2.5 1.87 1.7 Ex. 2 12% 18 63.36 29.8 21.50.212 0.185 0.18 6.56 3.08 2.23 Ex. 3 18% 18 2160 756.98 300 20 0.3750.375 223.7 78.39 31.07 Ex. 4 24% 24 12000 1799 530 13 0.791 1.6 1657248.4 54.89

TABLE 2 Ex. 1 Ex. 2 Ex. 3 Ex. 4 F/C of carbon fluoride mixture 0.5 0.50.5 0.5 Added amount of carbon fluoride 6% 12% 18% 24% mixtureVolumetric resistance (Ω · cm) 2 V 3.3 × 10⁸ 5.4 × 10⁶ 4.4 × 10⁶ 3.5 ×10⁶ Specific dielectric constant 1 kHz 2.5 6.6 224 1657 Dielectric loss1 kHz 0.04 0.212 20 13 Contact angle (degree) Water 99.2 106.1 110.5116.7 Hexadecane 49.7 47.6 48.5 50.2 Friction coefficient (Steel ball φ3mm, 0.20 0.29 0.27 0.29 1 Kg load, 0.2 cm/sec) 12 rpm 160 207 630 977Viscosity of paint (mPa · s) (Brookfield 60 rpm 133 156 313 427viscometer Rotor No. 2)

TABLE 3 Ex. 5 Ex. 6 Ex. 1 Ex. 7 Ex. 8 F/C of carbon fluoride mixture 0.10.3 0.5 0.7 0.9 Mixing ratio of carbon fluoride 5:95 39:61 62:38 78:2289:11 particles¹⁾ Added amount of carbon fluoride 6% 6% 6% 6% 6% mixtureVolumetric resistance (Ω· cm) 2 V 5.3 × 10⁶ 4.0 × 10⁷ 3.3 × 10⁸ 3.2 ×10¹³ 5.9 × 10¹⁴ Specific dielectric constant 1 kHz 29.4 17.6 2.5 2.2 2.4Dielectric loss 1 kHz 5.8 3.3 0.04 0.12 0.01 Contact angle (degree)Water 108.2 100.7 99.2 96.8 97.2 Hexadecane 50.0 49.2 49.7 47.5 51.1Friction coefficient (Steel ball φ3 mm, 0.31 0.29 0.20 0.21 0.21 1 Kgload, 0.2 cm/sec)  6 rpm 675 316 160 128 122 Viscosity of paint (mPa ·s) (Brookfield 12 rpm 480 255 151 130 122 viscometer Rotor No. 1)¹⁾Mixing ratio of the completely fluorinated carbon fluoride particles(F/C = 1.15) to the slightly fluorinated carbon fluoride particles (F/C= 0.08)

EXAMPLES 9 TO 11 Dielectric Property of Sheet

A sheet of 1 mm thick was obtained from the following omposition underthe following kneading conditions and rosslinking conditions.

(Composition)

Daiel G-501NK (available from Daikin Industries, Ltd.) 100 partsKYOWAMAG MA-30 (available from Kyowa Chemical  15 parts Industries,Ltd.) Crosslinking agent V-3 (available from Daikin  3 parts Industries,Ltd.) Carbon fluoride (F/C = 0.3) (Example 9)  6 parts (Example 10)  10parts (Example 11)  15 parts

The carbon fluoride mixture used was prepared in the same manner as inExamples 1 to 8.

(Kneading conditions)

Twin rolls, Roll distance: 0.5 mm,

Kneading time: 30 minutes

(Crosslinking conditions)

First vulcanizing: 170° C.×20 minutes at 35 kg/cm²

Secondary vulcanizing: 200° C.×24 hours in a hot air circulation typeelectric oven

With respect to this sheet, the same measurements as in Example 1 weremade.

The results are shown in Table 4.

TABLE 4 Added amount of carbon Coating Specific dielectric fluoridethickness Electrostatic capacity Dielectric loss mixture mixture (μm) 1kHz 1 MHz 10 MHz 1 kHz 1 MHz 10 MHz 1 kHz 1 MHz 10 MHz Ex. 9  6% 1.152.98 1.59 0.962 0.041 0.26 0.33 19.72 10.52 6.365 Ex. 10 10% 1.25 5.642.56 1.6 0.091 0.294 0.299 40.56 18.41 11.51 Ex. 11 15% 1.35 215.9612.59 — 0.453 — — 1677 97.79 —

As it is clear from the results of Tables 1 to 4, a desiredsemi-conductivity and high dielectric property can be obtained byadjusting a degree of fluorination and adding amount of carbon fluorideparticles. Also it is clear that in any cases, a high non-tackifyingproperty is obtained.

INDUSTRIAL APPLICABILITY

The image forming member provided thereon with the surface layerobtained by applying the paint of the present invention containing thecarbon fluoride composition has semiconductivity, non-tackifyingproperty, and particularly high dielectric property, namely a specificdielectric constant of not less than 10 at 25° C. at 1 kHz. The imageforming member is high in charging efficiency and image-transferringefficiency, is excellent in feeding property and separating property ofpapers and is free from jamming of papers, thus giving a good imagestably.

What is claimed is:
 1. A carbon fluoride composition comprising carbonfluoride particles and at least one selected from the group consistingof resins and rubbers, said composition possesses semi-conductivity andnon-tackifying property and has a specific dielectric constant of notless than 10 at 25° C. at 1 kHz, wherein said carbon fluoride particlesare obtained by fluorinating a carbon black at 200° to 600° C. and are amixture of completely fluorinated carbon fluoride particles and slightlyfluorinated carbon fluoride particles having a molar ratio F/C offluorine atom to carbon atom of not more than 0.1.
 2. The carbonfluoride composition of claim 1, wherein said resin is afluorine-containing resin and said rubber is a fluorine-containingrubber.
 3. The carbon fluoride composition of claim 1, wherein avolumetric resistance of the composition can be regulated within therange of from 10⁴ to 10¹² Ωcm and can give an image forming memberhaving a difference in volumetric resistance between any points onsurface of the member within one order.
 4. The carbon fluoridecomposition of claim 1, wherein an angle of contact to water is not lessthan 90 degrees.
 5. A paint comprising the carbon fluoride compositionof claim 1 and a liquid carrier.
 6. An image forming member forelectrophotographic copying machines which comprises an electricallyconductive supporting body having a surface layer formed by applying apaint comprising the carbon fluoride composition of claim 1 and a liquidcarrier.
 7. An image forming member for electrophotographic facsimilemachines which comprises an electrically conductive supporting bodyhaving a surface layer formed by applying a paint comprising the carbonfluoride composition of claim 1 and a liquid carrier.
 8. An imageforming member for electrophotographic printers which comprises anelectrically conductive supporting body having a surface layer formed byapplying a paint comprising the carbon fluoride composition of claim 1and a liquid carrier.